1. Field of the Invention
The present invention relates to a sliding member made of an aluminum (Al) bearing alloy having anti-seizure property and, more particularly, to a sliding member of the type mentioned above having a chemical conversion coating formed on the sliding surface thereof.
2. Background of the Invention
Aluminum bearing alloys have been known such as Al-Zn-Si-Cu-Pb system alloy (hereinafter referred to "first alloy") disclosed in JP-B-57-14742 and an alloy which is prepared by adding one, two or more of Mg, Ni and Bi. These aluminum bearing alloys are usually used in such a state that surface coating films are formed thereon by electroplating but in some cases used without any surface coating according to alloy composition.
Aluminum bearing alloys having no surface coating, however, are often unsatisfactory in that they do not exhibit conformability and anti-seizure property with respect to the mating sliding members. On the other hand, formation of coating film by electroplating requires a strict control of plating solution, as well as a complicated processing.